Spec Tyrannosauridae
The following is part of the Speculative Dinosaur Project pages. Nian, Smilotyrannus minor sinensis, and shantank, Ceronychoides gravis (eastern Asia) The mere mention of “meat-eating dinosaur” conjures up mental images of the bloodthirsty tyrannosaurs, the most infamous of the large carnivorous dinosaurs to us puny humans. Mounted skeletons of the infamous †''Tyrannosaurus rex'', the terror of the Late Cretaceous, are a guaranteed drawcard to any museum gallery. For the spexplorer, the prospect of seeing living, breathing tyrannosaurs is both a thrilling and fearful prospect. It is thus, difficult to decide whether to be relieved or disappointed upon discovering that most of Spec's tyrannosaurs are small, fluffy critters not much bigger than a wolf. Tyrannosauroids are highly specialised basal coelurosaurs, easily recognised by their disproportionately large heads and tiny forelimbs. They have invested nearly all their firepower into their teeth and jaws, resulting in big, boxy skulls powered by massive musculature. Certain skull-bones have fused together, leading to a trade-off of facial flexibility in exchange for greater strength. The (as usual) curved, serrated teeth are extremely broad in cross-section, unlike the flat blades most other predatory theropods which are adapted to cutting hide and meat but not to break bones. To support the heavy head, the neck is short and extremely well-muscled. The arms are greatly reduced in size (but usually not strength), having at most only two functional fingers, while the hindlimbs are large and powerful. All of Spec’s living tyrannosaurs belong to the Errosauriodea, which are notable for their furry adult-coats, fused metatarsals. HISTORY Tyrannosauroids probably arose from small coelurosaurian ancestors towards the end of the Jurassic Period with the fragmentary †''Stokesosaurus clevelandi'' and †''Aviatyrannis jurassica'' being early members of this clade. The earliest well known primitive tyrannosauroids are the Early Cretaceous †''Eotyrannus lengi'' from Britain, a sleek 5 metre predator with relatively long forelimbs, and the coeval †''Dilong paradoxus'' from northeastern China, an animal the size of a strider. During the Late Cretaceous, the familiar short-armed giants of the family Tyrannosauridae were the dominant large carnivores throughout the northern hemisphere, producing such well known forms as †''Tyrannosaurus rex'' and †''Tarbosaurus bataar''. In Spec, tyrannosaurids such as these continued to thrive up until 55 million years ago. Then the 14-metre long terrors seem to have suddenly disappeared. The sudden and drastic rise of global temperatures at the start of the Eocene may have contributed to this extinction, but the cause usually assumed today is different. At this very time, India made its first land contact with Asia and debarked its freight of endemic Gondwanan animals. Some seem not to have survived the competition with the northern fauna; for example abelisaurs have so far not been found in sediments between 55 and 25 million years in age in India or elsewhere in the northern continents. Others, however, had no competition. They immediately spread to Asia, North America, and then Europe. Among those are the Ranidae (the "Real True Frogs”) and the †Carcharodontosauridae. These, on average, humongous predators possessed fearsome thumb claws and long snouts lined with narrow, triangular, finely serrated teeth – ideal equipment for dispatching the extra-huge titanosaurs and ceratopsids of the time. Perhaps more importantly, they were adapted to ambushing, much like the much smaller deinonychosaurs. This hunting method worked very well in the dense rainforests that blanketed much of the Eocene world; tyrannosaurs, on the other hand, were and are specialists for long-distance pursuit. Some tyrannosaurs, however, found a way to escape the competition: they shrank. Among the many superb fossil finds of the mid-Eocene Messel Shales are three exquisitely preserved specimens of the little tyrannosaurid †''Saltotyrannus''. At just over a metre in length, this creature resembled a hatchling †''Tyrannosaurus'' with long, slender legs, which enabled it to run after the earliest jackalopes, and the fluffy chick-down that would normally be lost in adulthood. However, the level of ossification proves these specimens to be adults, as if the eggs found in the body cavity of one specimen weren’t enough. It would seem that a freak, neotenous mutation had created a hatchling-like tyrannosaur that retained its small size and insulatory covering into maturity, producing a diminutive predator that was well suited to the dense tropical jungles of Eocene Europe. These small, fluffy killers almost certainly gave rise to the first errosaurids and smilotyrannids during the Oligocene. ERROSAUROIDEA (extant Spec tyrannosaurs) All living tyrannosauroids belong to a single, but very diverse lineage, the Errosauroidea, which contains over thirty living species. Immediately noticeable on any errosaurid are the furry protofeathers that cover almost the entire body. Beneath this fluffy-coat are a suite of adaptations that have allowed the errosaurs to become the most highly cursorial of all living theropods – these dinosaurs can not only move fast but can maintain pursuit over considerable distances. The three metatarsal bones become fused, greatly strengthening the foot. The craniofacial air-sac system is very well developed, helping to keep the animal cool during lengthy physical exertions. The errosauroids can be divided into two large subclades: the errosaurids (striders, khinners and cazadins) and the smilotyrannids (bruisers and sabre-tyrants). ERROSAURIDAE (Striders and khinners) Most of the errosauroids' current diversity resides within Errosauridae, a group of long-legged predators similar to the ancestral errosauroid. They are generally small animals, rarely over two metres long. However, their bone-crushing bite more than makes up for their lack of size and for their greatly reduced arms. Striders have a distinctly heterodont dentition, with a series of conical front teeth for grasping prey followed by rows of backward-curved serrated teeth adapted for slicing flesh. One of these predators will catch small prey with its front teeth, getting a firm grip before throwing its head back and transferring the animal to its slicing rear teeth, which funnel food into the gullet. Taiga striders (Errosaurus aragorni) are ubiquitous on the steppes of northern Eurasia. Pursuit-predators of surpassing skill, these six-meter-long striders hunt the formosicorn herds, running a hapless shantank to exhaustion before ripping the animal apart with powerful tyrannosaurian jaws. Larger segnosaurs are left to pack-hunting draks and giant sabre-tyrants. Sketch of a taiga strider, Errosaurus aragorni (northern Eurasia) Strider eating an ammonite (North Sea coast) The khinner is a small and swift errosaurid that lives in Mongolia and northeastern China. area! Preferring smaller prey than their cousins, the striders, khinners generally target mammals and birds as food, although they will often gather into packs and attack small segnosaurs during times of famine. Khinner, Errosauroides mongoliensis (eastern and central Asia) The courour (Errosaurus erronis) is a typical North American relative of the khinner, being quite small (1.7 m long) and slight, with a coat of insulating plumage and atrophied arms. These little tyrannosaurs range across the northern prairies, where they hunt singly for small game or occasionally gather together to hunt segnosaurs or (in summer) singers. Oakley, anniae (North American grasslands) While courours are the dominant small-game predators on grasslands across North America, they are by no means the only carnivore in that habitat. Oakleys (? anniae) are solitary pursuit predators, running down game such as viris, young hmungos and even jackalopes, and killing them with a quick bite to the spine. In a sense, they are the equivalent of the cheetaurs of Africa and India. Oakleys also may scavenge from buffalo-bill kills, though these relatively puny errosaurs are careful to keep well out of the way of the massive sabre-tyrants. As with many tyrannosaur species, female oakleys are larger than males, often reaching lengths of four metres. This size disparity reflects the oakleys' nesting behavior, with the female rearing and protecting her chicks without help from her mate. NOTOVENATORINAE (Cazadins) When the first grasslands appeared in North America in the Miocene, singers and jackalopes took advantage of this new habitat, evolving adaptations of teeth and jaw musculature to grass-eating, as well as adaptations to fast, energy-saving locomotion to follow the rainfalls and to stay away from predators in the cover-poor landscape. This is, however, not a problem for a sufficiently fast and endurant errosaurid, such as a cazadin. As a rule, cazadins posses less plumage than their cousins (indeed, some are almost bald), and most are extremely gracile, with very long legs and a stiffened tail. However, the most obvious distinguishing feature between the two groups is the notovenatorines' toes (or lack thereof). All members of the clade Notovenatorinae posses only the two outer toes of the foot, the inner two toes being atrophied to mere slivers of bone, invisible beneath layers of skin and muscle. These creatures also tend to run on the very tips of their toes, giving them a distinctive, ostrich-like gait. Cazadins can still be found in the prairies of southern North America, but their diversity is greatest in South America which they first reached 3 million years ago and found empty of competition, the last noasaurs having died out a few hundred thousand years before. White cazadin, Papiliotyrannus pauli (central South America) South America is a continent of strange wonders, with giant armoured turtles, lanky pachas, and tiny, fleet-footed tyrannosaurs. Of these last, the metre-long white cazadin is the most common, a ubiquitous small predator of the pampas. White cazadins range from just south of the Amazon to Patagonia, and eat a variety of small dinosaurs, mammals, reptiles, and invertebrates. These solitary predators have even been observed to eat poisonous snakes, pinning the reptiles to the ground with their powerful feet before biting off the head. During the mating season, male white cazadins develop a yellow tinge to their head and neck feathers, while their brow ridges turn blue and their tiny, atrophied arms flush red. This trait has earned the white cazadins their scientific name which they share with the deseado dancer. Deseado dancer, Papiliotyrannus rancori (southern South America) The deseado dancer is a medium sized cazadin. These agile dinosaurs live in small pockets across southern South America. The solitary cazadins hunt a wide variety of prey, from mammals to viriosaurs to young dinoceratopsians. At 50 kg, the cazarrino (Notovenator pictus) is a typical South American cazadin. The behavior of the cazarrinos is not so typical, however, as these little hunters travel in packs of up to ten indivduals. Cazarrino packs hunt the fleet-footed viriosaurs of the pampas, running old or sick herd members to exhaustion before dispatching their prey with a powerful bite to neck. Cazarrino, Notovenator pictus (southern South America) A close relative of the cazarrino, the dwarf cazadin (Notovenator agressivissmus), lives along the montane streams of the southern Andes. Dwarf cazadins have a pronounced taste for fish, and are most often seen hunting along fast-moving rivers, although the little tyrannosaurs will readily pursue birds or mammals as well. Dwarf cazadin, Notovenator agressivissimus ''(South-Eastern South America) SMILOTYRANNIDAE (Bruisers and sabre-tyrants) The bruisers and sabre-tyrants constitute the second great branch of Errosauroidea. Their origin is, again, thought to be connected to the carcharodontosaurs. While those hulks were superbly adapted to sawing chunks of meat out of a large body, they were unable to process bones. Tyrannosaurs, on the other hand, mean business when they bite. Coprolites of †''Tyrannosaurus already contain fragmented bones, and †''Triceratops'' skeletons have been found with scratches that indicate a †''Tyrannosaurus'' made sure it had scraped all meat off the bones. This efficient prey processing allowed fairly large tyrannosaurs that specialized towards scavenging to coexist with the mighty carcharodontosaurs. Indeed, such tyrannosaurs, the Smilotyrannidae, evolved soon after the carcharodontosaurs had taken over the northern hemisphere; late Eocene strata on all three northern continents have yielded the distinctive thick teeth of smilotyrannids. When the carcharodontosaurids died out in the Miocene, some smilotyrannids took over their role. Contusavis (Bruisers) The bruisers (Contusavis) are the bullterriers of the errosaurs, powerful brutes that compress all the power and ferocity of their distant Cretaceous ancestors into a frame only a few metres long. Having split off soon after the errosaurs evolved their downy coats, bruisers developed in the direction of scavengers. Like the hyaenas of Home-Earth, bruisers are squat, compact predators, with powerful jaws, bone-crushing teeth similar to those of a crunchercroc, and a keen sense of smell. Bruisers live all over the Americas and those parts of Eurasia that are too cold for crunchercrocs. The forest bruiser (Contusavis belligerans) is a powerful, 1.8-metre-long hunter-scavenger that tracks prey and carrion through the dim recesses of Eurasia's northern forest, mostly by dint of its excellent senses of hearing and smell. Carrion, even in advanced decay, can be quickly dispatched with a bruiser's bone-crushing teeth, and live animals fare little better against these snapping jaws. Although not capable of fast sprints, bruisers are tenacious in their pursuit of prey, and may track a wounded animal for days. Forest bruiser, Contusavis belligerans (northern Eurasia) Larger than the forest bruiser, the Siberian bruiser (Contusavis ferox) is still smaller than most of the taiga's predators. This ferocious hunter-scavenger's small size, however (never longer than two metres), belies a formidable bellicosity. Like all bruisers, the Siberian is heavily-built and squat, with short legs and powerful head and neck muscles powering huge bone-crushing teeth. Siberians, more social than their forest-dwelling cousins, will gather into packs that track hunting striders. The more fleet-footed errosaurs having made their kill, the bruisers will rush in screeching, teeth gnashing, and drive their foes from their prey. The bruisers then settle down to apart the carcass, and jaws capable of exerting a pressure of ["3,000 pounds per square inch of force" to bear on their dinner soon reduce a segnosaur skeleton to a bloody smear in the grass, leaving few scraps for smaller scavengers. When forced to actively hunt, Siberian bruisers are capable of cooperative behavior of surprising complexity, usually picking an old or sick member of a herd and bringing it down with bites to the feet. Siberian bruiser, Contusavis ferox (Northern Eurasia) Smilotyrannus (Sabre-tyrants) The sabre-tyrants of Spec are arguably the most famous of this world's fauna. With their elongated, canine-like teeth, these immense predators roam throughout Eurasia and the Americas, preying upon the largest herbivores. These teeth are a comparatively recent phenomenon and are a specialized adaptation used to bring down giant therizinosaurs. Not only do these aggressive herbivores possess wicked claws (making a stand-up fight against one a suicidal prospect), but their flesh is covered in a dense layer of feathers and thick, fat-laden skin. A conventionally-toothed tyrannosaur going in for the kill against one of these brutes would likely end up with a mouthful of fluff and lard plus one very ticked-off therizinosaur looking down at him. When the carcharodontosaurids died out, the sabre-tyrants thus abandoned the massive chomping techniques of their bruiser-like ancestors in exchange for a more refined and precise armour-piercing attack aimed at strategically disabling its prey rather than crunching it with one bite. The first maxillary teeth became greatly elongated and narrower, becoming graceful stabbing blades. A single bite would easily drive these sabres through a therizinosaur's hide, leaving deep wounds that would severely weaken the animal through shock and blood-loss. A sabre-tyrant attack thus involves one or two quick hit-and-run strikes followed by a more leisurely final deathblow once the prey has been sufficiently weakened. Despite their impressive appearance, the elongated teeth are fragile and are frequently broken, but the tyrannosaurs have one huge advantage over their extinct Home-Earth mammalian counterparts – their sabres grow back. If a true, false or marsupial sabre-toothed cat of our home timeline broke its canines, it was a very sorry kitty indeed. However, the loss of a sabre for a smilotyrannine is of little consequence since its teeth are continually replaced throughout its life and it can, if healthy, scrape out a living through scavenging or driving draks from their kills in the weeks needed for the new sabres to erupt and grow. The vast, wind-swept arctotitan steppes around the Arctic Circle are home to a surprising diversity of hardy creatures that exploit the rich plant growth that takes place during the long days of the arctic summer. In order to withstand the winter cold and to be able to carry more fat reserves, many arctic animals are larger than their relatives. One is a true monster. The imperial sabre-tyrant, at over ten metres in length, is the largest terrestrial carnivore on the planet, uncomfortably reminiscent of such lost giants as †''Tyrannosaurus'' and †''Giganotosaurus'', and the only predator large enough to live off the arctotitan herds that graze in the arctotitan steppe. Unlike its warm-weather predecessors, however, the imperial sabre-tyrant is a denizen of the deep Arctic. Imperial sabre-tyrant, Smilotyrannus imperator imperator ''(northernmost Eurasia) The imperial sabre-tyrant has not changed appreciably since the Pleistocene, except for its size, which has waxed and waned with the ice ages. This massive predator is a runner, not as fast as its smaller cousins, the striders, but easily fast enough to pursue the lumbering arctotitans. An imperial sabre-tyrant relies both on strength and agility to combat these heavily-armed therizinosaurs. Long legs sweep the body out of reach of the herbivore's finger talons, a thick neck pushes the blunt-snouted face toward the prey's unprotected flank, extremely powerful arms anchor the prey in place, and teeth as long as a man's arm slice past the thick layers of feathers and blubber to the steaming muscle below. Imperial sabre-tyrants are masters of the bleed-to-death hunting strategy employed by their extinct cousins, the tyrannosaurids, as well as their closest counterparts in our home timeline, the sabre-toothed cats. Their incredibly long fangs, coupled with the typical tyrannosaurian battery of D-cross-sectioned scooping teeth at the front and slicing, steak-knife teeth toward the rear, create a flesh-cutting machine that can gouge huge chunks out of muscle, slice tough tendons apart, and rip a vertebral column to splinters. An imperial sabre-tyrant will inflict the worst damage it can upon its victim, then dash back to safety and wait for the hapless creature to expire from shock and blood loss before returning to feed. Imperial sabre-tyrants are not particularly social; indeed, their ferocious territorial instincts keep them separated almost all year. The single exception to their normal aggressive behavior takes place during the mating season in spring, when the males range about looking for prospective brides. Courting is brief, and the suitor, in mortal dread lest he be devoured by his lady, departs as soon as possible. The female lays her clutch of 4 – 6 eggs soon after in a volcano-shaped mound and incubates them with fermenting vegetable matter. The tiny, helpless chicks hatch quickly, and the doting mother takes excellent care of her children. Sabre-tyrant mothers often carry their progeny around in their mouths, carefully spitting the chicks into some secluded pile of brush before going off to hunt. She will continue to care for the chicks all through their first winter, finally leaving them to fend for themselves as the Arctic's brief spring passes. They must then set off to establish their own territories, never to see their mother again. For all their prowess in the hunt, imperial sabre-tyrants are a dying breed. They are almost completely specialized upon the arctotitans for their food, and the end of the last ice age has seen a drastic reduction of the giant herbivores' tundra habitat. The imperial sabre-tyrant can now only be found on the icy plains around the Arctic Circle, in both Siberia and northern Canada, although fossils indicate they once ranged as far south as southern France. Without doubt, it is the lack of human intervention that has saved these magnificent predators from the fate of the sabre-toothed cats of our own timeline. Imperial sabre-tyrant The thunderbird (''Smilotyrannus imperator brontus) is the largest carnivore of North America. Camouflaged plumage and short legs aid the thunderbird in running quickly through forests. Thunderbird, Smilotyrannus imperator brontus (northernmost North America) The raalo is a medium-sized saber tyrant that lives in Europe and western and northern Asia. During the summer, raalos live alone or in pairs, but during the winter they gather together into small packs. Though raalos are only 6 – 7 meters long (the female is always larger), they can bring down full-grown mooras and dorsas. During the summer, the raalo gathers fat to the base of its tail. Raalo, Smilotyrannus minor minor ''(western and northern Eurasia) The nian (''Smilotyrannus minor sinensis) is smaller but relatively more robust than the imperial sabre-tyrant. Like its larger cousin, the nian is a solitary hunter. Nians live in central and eastern Asia north of the Himalayas. Nian, Smilotyrannus minor sinensis (central and eastern Asia) Profile of a nian Tiina Aumala, Daniel Bensen, David Marjanović, Brian Choo and David Namen Category:Speculative Dinosaur Project Category:Old Wiki Page